A Collection of R/C Modelling Tips - RC World

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If the piston has a ring, it should be polished, with no nicks, and obviously be unbroken. If you replace the ring, it'sa good idea to replace the sleeve, too, and vice-versa.The back plate will have marks from the crankpin. That's okay, as long as they are not deep scratches. This wouldindicate bad bearings or a torqued crank. Rare.Clean any crap out of the inside of the motor. Don't worry too much about the castor varnish--just use acastor/synth blend for a while. The motor should be spotlessly clean inside before reassembly.Assembly:1. Heat the case again (not the bearings). Push the bearings into their bores using a wood-padded vise and justenough pressure to move them, and no more. Oil them with castor or 3-in-1.2. Drop the crankshaft in. Oil. Hold it on there with the thrust washer, a prop hub, nut washer and nut.3. If you have a ringed engine, oil the piston, ring, and inside of sleeve. Find the pin in the ring slot, and place thering gap there. (That is the only way you can compress the ring all the way around. Press the ring in with yourfingers and slip the piston into the bottom of the sleeve. There should be a shoulder on the inside of the bottomedge of the sleeve to help you with this. Be gentle, it doesn't take force, and you can easily break the ring. Get theorientation right, same as you noted earlier.4a. If you had to remove the sleeve (6b, above) before the piston, just reverse the process. The sleeve will go ineasier if you oil the outside.4b. Otherwise, slip the sleeve in there (pay attention to orientation) and put the connecting rod on the crank pin.Make sure the ports all line up just perfectly. Push the sleeve up using the wood in the port and turn it if you haveto.(Oh, you needed to reattach the front and back crankcase halves in here somewhere. :-)5. Install back plate.6. Install cylinder head, criss-cross pattern on the screws. If there was a piston fence (a raised ridge on the pistonface), get the orientation of the head so the slot matches up to it.7. Install the carb. Push pretty hard when seating it; you don't want air leaks there.8. Glow plug.And there you have it. Maybe an hour, assuming you need to replace the bearings. Don't kill the screws, and usenon-permanent locktite if you are worried about them backing out.Dave Svoboda, Palatine, ILStorage of your Ni-Cd R/C Packs"How should I store my batteries at the end of the season? What should I do to them when I put them back inoperation?"The batteries should be removed from the transmitter and plane for longer term storage. Here in the south where alot of us work out of our garage work shops I recommend putting them in the refrigerator (not the freezer) during theoff season. While not so important where your workshop rarely gets above 23 degrees C (74 F) the refrigerator isstill a good bet. Why? The failure mode of Ni-Cds is separator failure, this is the material that keeps the plates fromtouching each other. When it fails the cell shorts. At higher temperatures it oxidizes faster. In fact, the rate doublesfor every 10 degrees C increase."Should I store my batteries charged or discharged?" It doesn't really matter, they will self discharge in a fewmonths stored at room temperature. If you are going to store them in the refrigerator the charge will remain for a lotlonger so I would discharge them first to 4.4 volts and them put them away. Good cells will just set there in thedischarged condition (the voltage can vary considerably but is usually above 1 volt). In a battery with damaged"worn out" separator in the cells, the cells are apt to short if left in a discharged condition. This is actually goodsince it is the first indication of a cell that's going bad and it is best to replace the pack. A battery left on trickle
charge will seldom short out since it is in the charged condition and any short that tries to develop will be zapped bythe charge in the cell. Partial shorts (those having fairly high resistance) can be developing that can cause the cellsto self discharge at a higher rate than normal and possibly leave you short in the middle of a flight after you justmeasured the cell when it came off charge with your ESV and everything looked OK.The reason I recommend removing the batteries from the transmitter and plane is to protect against "black wire"disease. Should a cell short while in storage there is a high probability that there will be some leakage that can leadultimately to the "black wire" problem.Now when your batteries are coming out of storage, before charging, check the voltage without a load on thebattery. It should read well over 4.0 volts even if it has not been charged all winter. They should be essentially fullydischarged, flat as we say in the business. In this condition if the battery is going bad it will probably have shortedand you will read zero volts on that cell. It may be a soft short, one that could be blown away merely by the simpleaction of slow charging. Don't do it! It is just lying there waiting to bite you. Replace the pack. Cut out the "good"cells if you want and use them in something less critical than your model. If you have access to a cycler runningthough a couple of charge/discharge cycles is a good idea just to make sure you are getting the capacity you aresuppose to. Anything less than 80% of rated is suspect. Once at the field, pre-flight battery checks are in order,particularly at the beginning of the season. Since those that religiously check their flight packs with an expandedscale volt meter seem to crash less (due to battery failure) one must assume that the ritual is smiled upon by theR/C Gods.Now, back by popular demand, the pattern trimming chart:This chart was set up for trimming a pattern plane. However, there are quite a few sport aerobatic planes thatwould fly better if they were set up like pattern planes. It's a lot easier to fly a plane that's properly set up than aplane with all kinds of perverse mixing. I also must give credit where credit is due, this chart comes from theNSRCA (National Society of Radio Controlled Aerobatics) newsletter and was submitted by Mike Chipchase ofAustralia. Some of this information is repeated from the last article on trimming for aerobatics.First let's talk about basic airplane setup. The latest pattern designs are set up with 2.5 degrees of right thrust, 0degrees down thrust, .5 degrees positive incidence on the wing (root and tip, no washout), and 0 incidence on thestab. Or, .5 ~ 1 degree down thrust and 0 incidence on the wing. Use an incidence meter to check this, or block theplane up on a big flat table and use a scale accurate to 1/32nd of an inch. If the plans show this information usethat as a starting point.Control throws should be set up as shown on the plans. It's very important each aileron to have the same throw.This should be setup mechanically. The aileron throws should be set up the same up and down. If the plane hassplit elevators make sure that each elevator half has the same throw as the other half. I usually set the plane upwith more down elevator than up elevator. That way I'll have the same control authority for up or down elevator. Setup the rudder with about 30 ~ 35 degrees of throw. Of course the ailerons and the elevator need to be gap sealed.To start out, the CG should be placed as shown on the plans, or about 30% of the average chord. The CG can beadjusted later. Use the placement of the radio to place or move the CG if possible. This is better than addingunnecessary weight because light airplanes fly better than heavy ones. Since the battery pack is the heaviest partof the radio, its placement will have the biggest affect on the CG. Also, laterally balance the plane. Pick it upunderneath the center of the spinner and underneath the center of the tail. Place weight on the light wing tip untilthe plane balances. Embed the weight in the wing tip.With all that in mind here’s the chart.-----------------------------------------------------------------------To test for | Test procedure-----------------------------------------------------------------------Observations | Adjustments-----------------------------------------------------------------------Control Neutrals | Fly model straight and level-----------------------------------------------------------------------Trim for straight and level | Adjust clevices to center transmitter| trims.-----------------------------------------------------------------------Control throws | Fly model and apply full deflection| of each control in turn.-----------------------------------------------------------------------Check the response of each | Aileron Hi-rate 3 rolls in 4 sec.control | Lo-rate 3 rolls -n 6 sec. Elevator
Page 2 and 3: Moving the CG aft, within reason, c
Page 4 and 5: Always sand the edges smooth with f
Page 6 and 7: Now, using a belt sander (a disk sa
Page 8 and 9: A.Sometimes there's a need to conve
Page 10 and 11: Q.Wheel Axle BushingsA.If you have
Page 12: These are but a few thoughts on the
Page 15: mail everyday, waiting for them to
Page 19 and 20: side of model as roll |command. |C.
Page 21 and 22: Now that is dune you must have a Ba
Page 23 and 24: What is this fuel crossover like? C
Page 25 and 26: Ni-Cd Life - or why is down so quic
Page 27 and 28: Signed, the guy who has a nice deep
Page 29 and 30: The main difference between this me

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